The present invention relates generally to a ratchet device, and particularly to a ratchet device adaptable to use on prosthetic devices as an aid to manually handicapped individuals.
Prosthetic devices are used to provide mechanical substitutes for lost muscle control of limbs. For example specially designed hand braces fitted on a person's arm, writs, and fingers can allow a person some limited use of hands and fingers that are paralyzed. Some of these devices are advantageously equipped with ratchet devices that allow motion in one direction, but lock against motion in the opposite direction until released. For example, such a ratchet device on a hand brace equipped with appropriate mechanical linkages and connections can assist a person's paralyzed fingers to close and lock onto an object he desires to grip and to maintain such a grip until the ratchet is released.
Prior art ratchets used for these purposes have a number of shortcomings that have not heretofore been corrected. It is common for such devices to wear out rapidly, resulting in excess play and slop in the mechanical components and to be difficult to manipulate or operate. In order to maintain maximum effectiveness and use to a handicapped person, the ratchet must be right and secure in its operating mechanism over long periods of time with minimal wear or looseness in the moving parts. Yet, the ratchet mechanism must move freely and operate easily and smoothly with a minimum of maintenance. It is also preferable that such ratchet mechanisms be small and compact, yet durable and dependable, and they should be easily adaptable to both left and right hand use.